Stability of ZnMOx–SAPO-11 (OXZEO) composite catalysts for syngas conversion to gasoline

Abstract

The catalyst concept of oxide–zeolite (OXZEO) has been demonstrated in an increasing number of studies to be promising to tackle the selectivity challenge in syngas conversion and CO₂ hydrogenation. While significant progress has been achieved in product selectivity control, little work has been contributed to the catalyst stability of the OXZEO catalysts, which is essential for practical applications. Herein we studied the stability of ZnMO_x–SAPO-11 (M = Al, Cr, Mn) in syngas-to-gasoline, and observed slow deactivation within the initial 100 h reaction on stream. CO conversion decreased by 10–20% in 100 h depending on different oxide components. It was shown that the crystal sizes of ZnMO_x oxides increased slightly with time on stream. At the same time, accumulated carbonaceous species were also observed in the micropores of SAPO-11. A number of model reactions by exchanging the used and fresh metal oxides and zeotypes indicate that the changes of the physiochemical properties of both components during the reaction induced the decrease of CO conversion. Zeotypes can be regenerated by calcination in air.